Class V : EXTREMELY DIFFICULT - Long and violent rapids following
each other almost without interruption; riverbed extremely obstructed; big drops; violent current; very steep gradient

Class VI : DANGEROUS The difficulties of Class V carried to the extreme. Nearly impossible and very dangerous. For teams of experts only. Involves risk of life. Class VI rapids are not commercially raftable.

Note: The difficulty of a river may vary significantly with fluctuations in water level. The ratings listed usually refer to the rivers' difficulties at normal, summer levels. Don't judge a river by it's put-in pool and take-out, know what's downstream.